Conventionally, in data transmission technology, transmission systems of data signals and synchronous signals are defined by predetermined standards. For example, in a digital visual interface (DVI) which is an interface standard for input/output of video, and a high-definition multimedia interface (HDMI) which is an interface standard for input/output of video and sound, pulse width of horizontal synchronous signals, length of active periods of vertical synchronous signals, positions of valid periods of data signals (i.e., periods in which valid data exists), etc. are defined by a digital video transmission standard called “CEA-861D,” as shown in FIG. 15.
In recent years, in order to improve compatibility between devices, standardization has been promoted in various technical fields. For example, the HDMI has been widely used not only for digital electronic apparatuses such as digital televisions and DVD players but also in technical fields such as mobile apparatuses represented by digital cameras and mobile phones.